U.S. patent application number 14/899152 was filed with the patent office on 2016-05-19 for spring assembly for isolator.
The applicant listed for this patent is LITENS AUTOMOTIVE PARTNERSHIP. Invention is credited to James W. Dell.
Application Number | 20160138699 14/899152 |
Document ID | / |
Family ID | 52392532 |
Filed Date | 2016-05-19 |
United States Patent
Application |
20160138699 |
Kind Code |
A1 |
Dell; James W. |
May 19, 2016 |
SPRING ASSEMBLY FOR ISOLATOR
Abstract
In an aspect, a spring assembly is provided for an isolator, and
includes first and second helical compression springs, a retainer
and a spring housing. The first helical compression spring has a
central aperture and has a first end and a second end. The second
helical compression spring having a central aperture and having a
first end and a second end, wherein the second spring is coaxial
with and nested within the first spring. The retainer has a base
and a post that extends from the base into the central aperture at
the first end of the second helical spring. The spring housing that
has an interior space in which the first and second springs are
positioned, and further includes a base-engaging aperture that
holds the base of the retainer. The spring housing includes a drive
wall that is engaged with the first ends of the first and second
springs.
Inventors: |
Dell; James W.; (Newmarket,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LITENS AUTOMOTIVE PARTNERSHIP |
Woodbridge |
|
CA |
|
|
Family ID: |
52392532 |
Appl. No.: |
14/899152 |
Filed: |
July 25, 2014 |
PCT Filed: |
July 25, 2014 |
PCT NO: |
PCT/CA2014/000587 |
371 Date: |
December 17, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61858172 |
Jul 25, 2013 |
|
|
|
Current U.S.
Class: |
474/94 ;
267/168 |
Current CPC
Class: |
F16F 15/12346 20130101;
F16H 7/18 20130101; F02B 67/06 20130101; F16F 15/123 20130101; B60K
25/02 20130101; F16F 3/04 20130101; B60K 2025/022 20130101; F16H
2055/366 20130101; F16F 15/12326 20130101; F16F 1/12 20130101; F16F
1/125 20130101; F16H 55/36 20130101 |
International
Class: |
F16H 55/36 20060101
F16H055/36; F16F 3/04 20060101 F16F003/04 |
Claims
1. A spring assembly for an isolator or other torque transfer
device, comprising: a first helical compression spring and a second
helical compression spring, wherein each of the helical compression
springs has a central aperture and has a first end and a second
end, wherein the second spring is coaxial with and nested within
the first spring; a retainer having a base and a post that extends
from the base into the central aperture at the first end of the
second helical spring; and a spring housing that has an interior
space in which the first and second springs are positioned, and
further includes a base-engaging aperture that holds the base of
the retainer, wherein the spring housing includes a drive wall that
is engaged with the first ends of the first and second springs.
2. A spring assembly as claimed in claim 1, wherein the retainer is
made from a polymeric material.
3. A spring assembly as claimed in claim 1, wherein the spring is
made from a metal.
4. A spring assembly as claimed in claim 1, wherein the base
extends across the first end of both the first and second
springs.
5. A spring assembly as claimed in claim 1, wherein the spring
housing is made from two pieces
6. A spring assembly as claimed in claim 5, wherein the spring
housing includes a first piece and a second piece that together
define the base-engaging structure and provide a press-fit with the
base of the retainer.
7. A spring assembly as claimed in claim 1, wherein the first and
second springs are arcuate and have the same arc length.
8. A spring assembly as claimed in claim 1, wherein the first and
second springs are arcuate and have different arc lengths.
9. An isolator for isolating torsional vibration between an input
member and an output member, comprising: a first rotary drive
member that is engageable with one of the input and output members;
a second rotary drive member that is engageable with the other of
the input and output members; a first helical compression spring
and a second helical compression spring, wherein each of the
helical compression springs has a central aperture and has a first
end and a second end, wherein the second spring is coaxial with and
nested within the first spring; a retainer having a base and a post
that extends from the base into the central aperture at the first
end of the second helical spring; and a spring housing that has an
interior space in which the first and second springs are
positioned, and further includes a base-engaging aperture that
holds the base of the retainer, wherein the spring housing includes
a drive wall that is engaged with the first ends of the first and
second springs.
10. An isolator as claimed in claim 9, wherein the retainer is made
from a polymeric material.
11. An isolator as claimed in claim 9, wherein the spring is made
from a metal.
12. An isolator as claimed in claim 9, wherein the base extends
across the first end of both the first and second springs.
13. An isolator as claimed in claim 9, wherein the spring housing
is made from two pieces
14. An isolator as claimed in claim 13, wherein the spring housing
includes a first piece and a second piece that together define the
base-engaging structure and provide a press-fit with the base of
the retainer.
15. An isolator as claimed in claim 9, wherein the first and second
springs are arcuate and have the same arc length.
16. An isolator as claimed in claim 9, wherein the first and second
springs are arcuate and have different arc lengths.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 61/858,172, filed Jul. 25, 2013, the
contents of which are incorporated by reference as if fully set
forth in detail herein.
FIELD
[0002] The present invention relates to isolators and in particular
isolators for use between the engine crankshaft and an endless
drive member such as a belt.
BACKGROUND
[0003] An isolator is usually used for isolating a crankshaft
pulley and its associated belt (e.g. an accessory drive belt) from
torsional vibration from the crankshaft that is a result of
reciprocation of masses (e.g. pistons) in an internal combustion
engine, and in particular engines with certain cylinder counts such
as four- or- three cylinder engines, and diesel engines. Some
isolators incorporate two pairs of springs, where in each pair
there is one outer spring that has a central aperture and one inner
spring that is positioned in the central aperture of the outer
spring. Such isolators suffer from noise issues however, due to
sliding movement of the inner spring in the central aperture, since
in many cases the inner spring is shorter lengthwise than the outer
spring.
SUMMARY
[0004] In an aspect, a spring assembly is provided for an isolator
or any other suitable torque transfer device, and includes first
and second helical compression springs, a retainer and a spring
housing. The first helical compression spring has a central
aperture and has a first end and a second end. The second helical
compression spring having a central aperture and having a first end
and a second end, wherein the second spring is coaxial with and
nested within the first spring. The retainer has a base and a post
that extends from the base into the central aperture at the first
end of the second helical spring. The spring housing that has an
interior space in which the first and second springs are
positioned, and further includes a base-engaging aperture that
holds the base of the retainer. The spring housing includes a drive
wall that is engaged with the first ends of the first and second
springs.
[0005] In another aspect, an isolator is provided that includes the
spring assembly described above.
[0006] Other features and advantages will be apparent by following
the description with references to the drawings.
[0007] BRIEF DESCRIPTION ON THE DRAWINGS
[0008] The foregoing and other aspects of the disclosure will be
more readily appreciated by reference to the accompanying drawings,
wherein:
[0009] FIG. 1 is an elevation view of an engine with a crankshaft,
a driven belt and an isolator including a spring assembly in
accordance with an embodiment of the present invention;
[0010] FIG. 1a is a perspective right-side view of the isolator
shown in FIG. 1;
[0011] FIG. 2 is a perspective exploded view of the isolator shown
in FIG. 1a;
[0012] FIG. 4 is a perspective exploded view of first and second
springs and a retainer that are part of the isolator shown in FIG.
1a;
[0013] FIG. 5 is a perspective unexploded view of the springs and
the retainer shown in FIG. 4 assembled together;
[0014] FIG. 6 is a perspective view of the springs and retainer
shown in FIG. 5, mounted in part of a spring housing;
[0015] FIG. 7 is a perspective view of the springs and retainer
shown in FIG. 5, mounted in the complete spring housing, thereby
forming a spring assembly;
[0016] FIG. 8 is a perspective view of an alternative retainer that
can be used with the isolator; and
[0017] FIG. 9 is a perspective view of the two springs with the
retainer shown in FIG. 8.
DETAILED DESCRIPTION OF EMBODIMENTS
[0018] Reference is made to FIG. 1, which shows an isolator 10 for
transferring power between a crankshaft 12 on an engine 14 and an
endless drive member 16, such as an accessory drive belt, in
accordance with an embodiment of the present invention. The
isolator 10 isolates the endless drive member 16 from vibrations or
other sudden changes in torque in the crankshaft 12, and vice
versa.
[0019] As seen in FIGS. 2 and 3, the isolator 10 includes a pulley
18, a driver 20, first and second isolation spring assemblies 21,
which include at least one pair of first and second springs 22
(shown individually at 22a and 22b), a retainer 39, and an optional
spring shell 24.
[0020] The driver 20 is fixedly mountable in any suitable way to
the crankshaft 12 for rotation about an axis A. For example, a
shaft adapter 26 may be provided that mounts to the crankshaft 12
via a plurality of threaded fasteners (shown at 28 in FIG. 1) such
as four spline socket head cap screws that pass through apertures
in the adapter 26 and into threaded apertures 32 in the end of the
crankshaft 12.
[0021] The driver 20 may be made from any suitable material such as
a suitable metal, such as steel.
[0022] The shaft adapter 26 may include a support surface 34 for
supporting a bushing 36 that in turn supports a bushing engagement
surface 38 on the pulley 18 so as to permit relative rotation
between the pulley 18 and the crankshaft 12, the shaft adapter 26
and the driver 20. The bushing 36 may also include a radial lip
that acts as a thrust bushing portion that is engaged by and
supports the pulley 18 in the axial direction. The bushing 36 may
be made from any suitable material such as nylon.
[0023] The pulley 18 is supported for rotation relative to the
crankshaft 12 and is engageable with the belt 16. It will be noted
that the term `belt` is used for convenience, but instead it may be
any suitable endless drive member. Analogously, the term `pulley`
is used for convenience, but instead it may be any suitable rotary
member that is engageable with the endless drive member.
[0024] The pulley 18, in the embodiment shown has a belt engagement
surface 40 that is configured to engage a poly-V groove belt. The
pulley 18 may be made from two elements including a main portion
18a and a cover member 18b that is connected to the main portion
18a via any suitable means (e.g. by means of a press-fit). The
pulley 18 may be made from any suitable material such as a suitable
metal, such as steel.
[0025] The spring assemblies 22 elastically deform to isolate the
endless drive member 16 and the crankshaft 12 from vibrations or
other sudden changes in torque in one another. The spring
assemblies 22 in the examples each include first and second
arcuate, helical coil compression springs 22a and 22b wherein one
is nested within the other, and a retainer 39.
[0026] While two spring assemblies 22 are shown in FIG. 2, it will
be understood that the isolator could alternatively have a single
spring assembly 22 or three or more spring assemblies 22.
[0027] FIG. 3 shows only one spring assembly 22 in the spring
housing 24, for simplicity. Referring to FIGS. 3, 4 and 5, each
spring 22a and 22b has a first end, shown at 42a for spring 22a,
and 42b for spring 22b. Each spring 22a and 22b has a second end,
shown at 44a for spring 22a, and 44b for spring 22b. The first
spring 22a may be referred to as the outer spring 22a, and has a
central aperture 46 in which the second, or inner, spring 22b
extends. The second spring 22b also has a central aperture 47, as
shown in FIG. 4.
[0028] Referring to FIGS. 4 and 5, the retainer 39 includes a base
portion 102 and a projection 104. The post 104 extends from the
base 102 and fits snugly into the central aperture 47 at the first
end 42b of the second spring 22b. The spring housing 24 has an
interior space 106 in which the first and second springs 22a and
22b are positioned, and further includes a base-engaging structure
108 that holds the base 102 of the retainer 39. The spring housing
24 includes a drive wall 110 (made up of first and second drive
wall portions 110a and 110b) that engages the first ends 42a and
42b of the first and second springs 22a and 22b directly, so that
force transfer between both of the springs 22a and 22b and the
spring housing 24 takes place directly and not through the retainer
39.
[0029] As can be seen in FIG. 5, the base 102 extends across the
first ends 42a and 42b of both the first and second springs 22a and
22b.
[0030] When the springs 22a and 22b are positioned in the spring
housing 24, the first spring 22a will be in a slight state of
preload or compression. This pins the base 102 in the base-engaging
structure 108 and ensures that there is no movement between the
first spring 22a and the retainer 39. The second spring 22b remains
fixed in position relative to the first spring 22a by virtue of
being snugly mounted to the post 104 of the retainer 39.
[0031] The springs 22a and 22b may be made from any suitable
material such as a suitable metal such as steel.
[0032] The retainer 39 may be made from any suitable material such
as a polymeric material, such as nylon, or some other flexible
material that permits it to be snugly inserted into the central
aperture 47 of the second spring 22b.
[0033] While the spring housing 24 is shown as being a separate
structure from the pulley 18, it is alternatively possible for the
spring housing 24 to be integral with the pulley 18. The pulley 18
may engage the spring housing 24 in any suitable way, such as by
lugs on the pulley that engage lug receiving apertures in the
spring housing 24, and/or by a press-fit connection.
[0034] The driver 20 has a central body 48, a first arm 50a and a
second arm 50b. Each of the first and second arms 50a and 50b has a
first side 52 and a second side 56. The first side 52 is engageable
with the spring end 44a of one of the first springs 22 so as to
transfer torque therebetween. Furthermore, if the torque transfer
between the driver 20 and pulley 18 is sufficiently high to cause a
large amount of compression of the spring 22a, the first side 52 of
the arms 50a and 50b is engageable with the spring end 44b of the
second spring 22b, at which point both springs 22a and 22b act to
transfer torque between the driver 20 and the pulley 18. In general
torque transfer may take place from the driver 20 to the springs
22, and from the springs 22 to the pulley 18 through the spring
housing 24 substantially without transferring any of the force
through the retainers 39.
[0035] The retainers 39 serve to prevent the inner spring 22b from
sliding around in the central aperture 46.
[0036] Referring to FIG. 3, the spring housing 24 may be made from
two spring housing portions 24a and 24b, which may be assembled
together in any suitable way, such as by use of one or more clip
members on either or both housing portions 24a and 24b that engage
clip receiving shoulders configured to lockingly receive the one or
more clip members. The two housing portions 24a and 24b may
together define the base-engaging structure 108 and may provide the
press-fit with the base 102 of the retainer 39.
[0037] In the embodiment shown, the isolator 10 further includes a
seal member 88, a seal biasing member 90 and a dust shield 92.
These cooperate to prevent leakage of lubricant (e.g. grease) out
from the interior space of the pulley and to inhibit dust and
debris from entering into the interior space of the isolator 10.
The seal member 88 additionally acts as another thrust bushing
which is urged into engagement with the pulley 18 (specifically the
cover member 18b), by the seal biasing member 90, so as to urge the
pulley 18 and the bushing 36 over to a datum point against a
shoulder on the shaft adapter 26 at one end of the support surface
34. The dust shield 92 could instead be some other component such
as a torsional vibration damper that is connected indirectly to the
crankshaft 12 via the driver 20a and the shaft adapter 26 to reduce
the amplitude of angular reciprocation of the crankshaft 12 during
torsional vibration thereof, particularly at higher RPM.
[0038] A projection 94 (FIGS. 1a and 2) on the shaft adapter 26 may
be passed through apertures in the dust shield 92, the biasing
member 90, and the driver 20 to ensure alignment of these
components with the axis A. The projection 94 could be staked
afterwards so that all these components remain mounted to the shaft
adapter 26 to form a subassembly.
[0039] Reference is made to FIG. 8, which shows a retainer 139 that
is similar to retainer 39, and has a base 102, but which a post 111
that has circumferentially extending recesses 112. The recesses 112
engage coils from the inner spring 22b so as to better retain the
inner spring 22b thereon.
[0040] While the arc lengths of the springs 22a and 22b are shown
to be different (such that the arc length of the second spring 22b
is shorter than the arc length of the first spring 22a), it is
alternatively possible for two springs 22a and 22b to have the same
arc length.
[0041] In the embodiment shown, it has been described for the
isolator 10 to be installed on the crankshaft 12 of an engine 14.
It will be noted that the isolator 10 could alternatively be
installed on the shaft of an accessory that is driven by the belt
16, such as, for example on a shaft of a steering pump. In such an
embodiment, torque transfer would generally occur from the pulley
18 to the driver 20 and shaft adapter 26 through the isolation
springs 22. The driver 20, in such an embodiment, would drive the
shaft of the accessory instead of driving the pulley 18. Put more
broadly, the isolator 10 may be used on any engine for isolating
between any suitable input member (such as a belt, or a crankshaft)
and any suitable output member (such as an accessory input shaft,
or a belt). Additionally, the driver 20 is just one example of a
first rotary drive member, and the pulley is just one example of a
second rotary drive member. For example, the pulley 18 could
instead be a gear that drives a gear train and that is driven be
the engine crankshaft via the driver 20 and through the isolation
springs 22.
[0042] While the engine 14 may be a vehicular engine, it will be
understood that it could be a stationary engine used for an
industrial application or the like.
[0043] While the above description constitutes a plurality of
embodiments of the present invention, it will be appreciated that
the present invention is susceptible to further modification and
change without departing from the fair meaning of the accompanying
claims.
* * * * *